Hybrid interconnect device and method

Abstract

In an embodiment, a method includes: forming an interconnect including waveguides and conductive features disposed in a plurality of dielectric layers, the conductive features including conductive lines and vias, the waveguides formed of a first material having a first refractive index, the dielectric layers formed of a second material having a second refractive index less than the first refractive index; bonding a plurality of dies to a first side of the interconnect, the dies electrically connected by the conductive features, the dies optically connected by the waveguides; and forming a plurality of conductive connectors on a second side of the interconnect, the conductive connectors electrically connected to the dies by the conductive features.

What is claimed is: 
     
       1. A method comprising:
 patterning a portion of a substrate to form a waveguide, the substrate having a first surface and a second surface opposite the first surface; 
 depositing a first dielectric layer on the waveguide and the first surface of the substrate; 
 forming vias extending through the first dielectric layer; 
 depositing a plurality of second dielectric layers on the first dielectric layer; 
 forming a plurality of conductive features in the second dielectric layers, a first region of the second dielectric layers being free from the conductive features; 
 attaching a plurality of dies to the second dielectric layers, the dies being electrically connected to the conductive features, the dies being optically connected to the waveguide through the first region of the second dielectric layers; 
 thinning the second surface of the substrate to expose the vias; and 
 forming conductive connectors electrically connected to the vias. 
 
     
     
       2. The method of  claim 1 , wherein the substrate is formed of a material having a first refractive index, and the first dielectric layer is formed of a material having a second refractive index less than the first refractive index. 
     
     
       3. The method of  claim 1  further comprising:
 forming a laser source on the substrate, the waveguide extending continuously around the substrate, the laser source being optically coupled to the waveguide. 
 
     
     
       4. The method of  claim 1  further comprising:
 forming recesses in the waveguide to define a grating coupler in the waveguide. 
 
     
     
       5. The method of  claim 4 , wherein the conductive features are formed in a second region of the second dielectric layers, the first region of the second dielectric layers extending from the grating coupler to a top surface of the second dielectric layers. 
     
     
       6. The method of  claim 1 , wherein the substrate comprises a contiguous semiconductor material, and wherein the patterning the portion of the substrate to form the waveguide comprises:
 forming recesses in the contiguous semiconductor material, unrecessed portions of the contiguous semiconductor material forming the waveguide. 
 
     
     
       7. The method of  claim 1 , wherein the substrate comprises a semiconductor material on an insulator layer, and wherein the patterning the portion of the substrate to form the waveguide comprises:
 forming openings in the semiconductor material to expose the insulator layer, remaining portions of the semiconductor material forming the waveguide. 
 
     
     
       8. A method comprising:
 depositing a first dielectric layer around waveguides, the waveguides being formed of a first material having a first refractive index, the first dielectric layer being formed of a second material having a second refractive index less than the first refractive index; 
 forming a plurality of vias from a first side of the first dielectric layer to a second side of the first dielectric layer; 
 depositing a plurality of second dielectric layers on the first side of the first dielectric layer, the second dielectric layers being formed of the second material; 
 forming a plurality of conductive features in the second dielectric layers; 
 bonding a plurality of dies to the conductive features, the dies being electrically connected by the conductive features, the dies being optically connected by the waveguides; and 
 forming a plurality of conductive connectors on the second side of the first dielectric layer, the conductive connectors being electrically connected to the dies by the conductive features and the vias. 
 
     
     
       9. The method of  claim 8 , wherein the waveguides comprise grating couplers, and wherein the second dielectric layers are substantially free of conductive features in regions extending between the grating couplers of the waveguides and respective photonic integrated circuits. 
     
     
       10. The method of  claim 8 , wherein the bonding the plurality of dies to conductive features comprises:
 bonding the plurality of dies to the conductive features with hybrid bonding. 
 
     
     
       11. The method of  claim 8 , wherein the bonding the plurality of dies to the conductive features comprises:
 bonding the plurality of dies to the conductive features with conductive connectors. 
 
     
     
       12. A method comprising:
 depositing a first dielectric layer around a waveguide, the first dielectric layer having a first side and a second side opposite the first side, the waveguide comprising a material having a first refractive index, the first dielectric layer comprising a material having a second refractive index; 
 forming a plurality of vias extending from the first side of the first dielectric layer to the second side of the first dielectric layer; 
 depositing a plurality of second dielectric layers adjacent the first side of the first dielectric layer, the second dielectric layers comprising a material having a third refractive index, the second refractive index and the third refractive index being less than the first refractive index; 
 forming a plurality of first conductive features in first regions of the second dielectric layers, second regions of the second dielectric layers being free from the first conductive features; and 
 forming a plurality of second conductive features adjacent the second side of the first dielectric layer, the vias electrically connecting the second conductive features to the first conductive features. 
 
     
     
       13. The method of  claim 12  further comprising:
 providing a substrate comprising a contiguous semiconductor material; and 
 forming recesses in the contiguous semiconductor material, unrecessed portions of the contiguous semiconductor material forming the waveguide. 
 
     
     
       14. The method of  claim 13  further comprising:
 thinning the substrate such that the second side of the first dielectric layer and a bottom surface of the waveguide are planar. 
 
     
     
       15. The method of  claim 12  further comprising:
 providing a substrate comprising a semiconductor material on an insulator layer; and 
 forming openings in the semiconductor material to expose the insulator layer, remaining portions of the semiconductor material forming the waveguide. 
 
     
     
       16. The method of  claim 15 , wherein after forming the vias, the vias further extend through the insulator layer. 
     
     
       17. The method of  claim 12  further comprising:
 forming recesses in the waveguide to define a grating coupler in the waveguide, the first dielectric layer being further deposited in the recesses. 
 
     
     
       18. The method of  claim 12  further comprising:
 attaching a plurality of dies to the second dielectric layers, a first subset of the dies being electrically interconnected by the first conductive features, a second subset of the dies being optically interconnected by the waveguide. 
 
     
     
       19. The method of  claim 18 , wherein the first regions of the second dielectric layers are disposed between the first subset of the dies and the waveguide, and wherein the second regions of the second dielectric layers are disposed between the second subset of the dies and the waveguide. 
     
     
       20. The method of  claim 18  further comprising:
 forming a laser source, the laser source being optically connected to each of the second subset of the dies.